// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/component_updater/widevine_cdm_component_installer.h"

#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/base_paths.h"
#include "base/bind.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/native_library.h"
#include "base/stl_util.h"
#include "base/task/post_task.h"
#include "base/values.h"
#include "build/build_config.h"
#include "chrome/common/media/cdm_manifest.h"
#include "components/component_updater/component_installer.h"
#include "components/component_updater/component_updater_service.h"
#include "components/version_info/version_info.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/cdm_registry.h"
#include "content/public/common/cdm_info.h"
#include "crypto/sha2.h"
#include "third_party/widevine/cdm/buildflags.h"
#include "third_party/widevine/cdm/widevine_cdm_common.h"

#if defined(OS_LINUX)
#include "chrome/common/media/component_widevine_cdm_hint_file_linux.h"
#endif

#if !BUILDFLAG(ENABLE_WIDEVINE_CDM_COMPONENT)
#error This file should only be compiled when Widevine CDM component is enabled
#endif

using content::BrowserThread;
using content::CdmRegistry;

namespace component_updater {

namespace {

// CRX hash. The extension id is: oimompecagnajdejgnnjijobebaeigek.
const uint8_t kWidevineSha2Hash[] = {
    0xe8, 0xce, 0xcf, 0x42, 0x06, 0xd0, 0x93, 0x49, 0x6d, 0xd9, 0x89,
    0xe1, 0x41, 0x04, 0x86, 0x4a, 0x8f, 0xbd, 0x86, 0x12, 0xb9, 0x58,
    0x9b, 0xfb, 0x4f, 0xbb, 0x1b, 0xa9, 0xd3, 0x85, 0x37, 0xef};
static_assert(base::size(kWidevineSha2Hash) == crypto::kSHA256Length,
              "Wrong hash length");

// Name of the Widevine CDM OS in the component manifest.
const char kWidevineCdmPlatform[] =
#if defined(OS_MACOSX)
    "mac";
#elif defined(OS_WIN)
    "win";
#else  // OS_LINUX, etc. TODO(viettrungluu): Separate out Chrome OS and Android?
    "linux";
#endif

// Name of the Widevine CDM architecture in the component manifest.
const char kWidevineCdmArch[] =
#if defined(ARCH_CPU_X86)
    "x86";
#elif defined(ARCH_CPU_X86_64)
    "x64";
#else  // TODO(viettrungluu): Support an ARM check?
    "???";
#endif

// Widevine CDM is packaged as a multi-CRX. Widevine CDM binaries are located in
// _platform_specific/<platform_arch> folder in the package. This function
// returns the platform-specific subdirectory that is part of that multi-CRX.
base::FilePath GetPlatformDirectory(const base::FilePath& base_path) {
  std::string platform_arch = kWidevineCdmPlatform;
  platform_arch += '_';
  platform_arch += kWidevineCdmArch;
  return base_path.AppendASCII("_platform_specific").AppendASCII(platform_arch);
}

#if !defined(OS_LINUX)
// On Linux the Widevine CDM is loaded at startup before the zygote is locked
// down. As a result there is no need to register the CDM with Chrome as it
// can't be used until Chrome is restarted. Instead we simply update the hint
// file so that startup can load this new version next time.
void RegisterWidevineCdmWithChrome(
    const base::Version& cdm_version,
    const base::FilePath& cdm_install_dir,
    std::unique_ptr<base::DictionaryValue> manifest) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  // This check must be a subset of the check in VerifyInstallation() to
  // avoid the case where the CDM is accepted by the component updater
  // but not registered.
  content::CdmCapability capability;
  if (!ParseCdmManifest(*manifest, &capability)) {
    VLOG(1) << "Not registering Widevine CDM due to malformed manifest.";
    return;
  }

  VLOG(1) << "Register Widevine CDM with Chrome";
  const base::FilePath cdm_path =
      GetPlatformDirectory(cdm_install_dir)
          .AppendASCII(base::GetNativeLibraryName(kWidevineCdmLibraryName));
  CdmRegistry::GetInstance()->RegisterCdm(
      content::CdmInfo(kWidevineCdmDisplayName, kWidevineCdmGuid, cdm_version,
                       cdm_path, kWidevineCdmFileSystemId,
                       std::move(capability), kWidevineKeySystem, false));
}
#endif  // !defined(OS_LINUX)

}  // namespace

class WidevineCdmComponentInstallerPolicy : public ComponentInstallerPolicy {
 public:
  WidevineCdmComponentInstallerPolicy();
  ~WidevineCdmComponentInstallerPolicy() override {}

 private:
  // The following methods override ComponentInstallerPolicy.
  bool SupportsGroupPolicyEnabledComponentUpdates() const override;
  bool RequiresNetworkEncryption() const override;
  update_client::CrxInstaller::Result OnCustomInstall(
      const base::DictionaryValue& manifest,
      const base::FilePath& install_dir) override;
  void OnCustomUninstall() override;
  bool VerifyInstallation(const base::DictionaryValue& manifest,
                          const base::FilePath& install_dir) const override;
  void ComponentReady(const base::Version& version,
                      const base::FilePath& path,
                      std::unique_ptr<base::DictionaryValue> manifest) override;
  base::FilePath GetRelativeInstallDir() const override;
  void GetHash(std::vector<uint8_t>* hash) const override;
  std::string GetName() const override;
  update_client::InstallerAttributes GetInstallerAttributes() const override;
  std::vector<std::string> GetMimeTypes() const override;

  // Updates CDM path if necessary.
  void UpdateCdmPath(const base::Version& cdm_version,
                     const base::FilePath& cdm_install_dir,
                     std::unique_ptr<base::DictionaryValue> manifest);

  DISALLOW_COPY_AND_ASSIGN(WidevineCdmComponentInstallerPolicy);
};

WidevineCdmComponentInstallerPolicy::WidevineCdmComponentInstallerPolicy() {}

bool WidevineCdmComponentInstallerPolicy::
    SupportsGroupPolicyEnabledComponentUpdates() const {
  return true;
}

bool WidevineCdmComponentInstallerPolicy::RequiresNetworkEncryption() const {
  return false;
}

update_client::CrxInstaller::Result
WidevineCdmComponentInstallerPolicy::OnCustomInstall(
    const base::DictionaryValue& manifest,
    const base::FilePath& install_dir) {
  return update_client::CrxInstaller::Result(0);
}

void WidevineCdmComponentInstallerPolicy::OnCustomUninstall() {}

// Once the CDM is ready, update the CDM path.
void WidevineCdmComponentInstallerPolicy::ComponentReady(
    const base::Version& version,
    const base::FilePath& path,
    std::unique_ptr<base::DictionaryValue> manifest) {
  if (!IsCdmManifestCompatibleWithChrome(*manifest)) {
    VLOG(1) << "Installed Widevine CDM component is incompatible.";
    return;
  }

  // Widevine CDM affects encrypted media playback, hence USER_VISIBLE.
  // See http://crbug.com/900169 for the context.
  base::PostTask(
      FROM_HERE,
      {base::ThreadPool(), base::MayBlock(), base::TaskPriority::USER_VISIBLE},
      base::BindOnce(&WidevineCdmComponentInstallerPolicy::UpdateCdmPath,
                     base::Unretained(this), version, path,
                     base::Passed(&manifest)));
}

bool WidevineCdmComponentInstallerPolicy::VerifyInstallation(
    const base::DictionaryValue& manifest,
    const base::FilePath& install_dir) const {
  const base::FilePath cdm_path =
      GetPlatformDirectory(install_dir)
          .AppendASCII(base::GetNativeLibraryName(kWidevineCdmLibraryName));
  content::CdmCapability capability;
  return IsCdmManifestCompatibleWithChrome(manifest) &&
         base::PathExists(cdm_path) && ParseCdmManifest(manifest, &capability);
}

// The base directory on Windows looks like:
// <profile>\AppData\Local\Google\Chrome\User Data\WidevineCdm\.
base::FilePath WidevineCdmComponentInstallerPolicy::GetRelativeInstallDir()
    const {
  return base::FilePath::FromUTF8Unsafe(kWidevineCdmBaseDirectory);
}

void WidevineCdmComponentInstallerPolicy::GetHash(
    std::vector<uint8_t>* hash) const {
  hash->assign(kWidevineSha2Hash,
               kWidevineSha2Hash + base::size(kWidevineSha2Hash));
}

std::string WidevineCdmComponentInstallerPolicy::GetName() const {
  return kWidevineCdmDisplayName;
}

update_client::InstallerAttributes
WidevineCdmComponentInstallerPolicy::GetInstallerAttributes() const {
  return update_client::InstallerAttributes();
}

std::vector<std::string> WidevineCdmComponentInstallerPolicy::GetMimeTypes()
    const {
  return std::vector<std::string>();
}

void WidevineCdmComponentInstallerPolicy::UpdateCdmPath(
    const base::Version& cdm_version,
    const base::FilePath& cdm_install_dir,
    std::unique_ptr<base::DictionaryValue> manifest) {
  // On some platforms (e.g. Mac) we use symlinks for paths. Convert paths to
  // absolute paths to avoid unexpected failure. base::MakeAbsoluteFilePath()
  // requires IO so it can only be done in this function.
  const base::FilePath absolute_cdm_install_dir =
      base::MakeAbsoluteFilePath(cdm_install_dir);
  if (absolute_cdm_install_dir.empty()) {
    PLOG(WARNING) << "Failed to get absolute CDM install path.";
    return;
  }

#if defined(OS_LINUX)
  VLOG(1) << "Updating hint file with Widevine CDM " << cdm_version;

  // This is running on a thread that allows IO, so simply update the hint file.
  if (!UpdateWidevineCdmHintFile(cdm_install_dir))
    PLOG(WARNING) << "Failed to update Widevine CDM hint path.";
#else
  base::CreateSingleThreadTaskRunner({content::BrowserThread::UI})
      ->PostTask(
          FROM_HERE,
          base::BindOnce(&RegisterWidevineCdmWithChrome, cdm_version,
                         absolute_cdm_install_dir, base::Passed(&manifest)));
#endif
}

void RegisterWidevineCdmComponent(ComponentUpdateService* cus) {
  auto installer = base::MakeRefCounted<ComponentInstaller>(
      std::make_unique<WidevineCdmComponentInstallerPolicy>());
  installer->Register(cus, base::OnceClosure());
}

}  // namespace component_updater